Biodegradable polymer nanoparticles (NPs) are of great interest for drug delivery systems due to their outstanding biocompatibility and easy preparation. The major challenge for these systems is to tailor their degradation and drug release to the application they are aimed for. It is reported that tuning the thermal properties (TPs) of polyesters via changing their crystallinity affects those properties but is also mostly accompanied by a variation of the hydrophilic / hydrophobic balance (HHB). This causes a knowledge gap on how the TPs of polymers affect their degradation and drug release without the influence of the HHB as third variable. In order to tackle that issue, our approach is to create polyester based NPs with different TPs, where the HHB is kept constant. This presentation portrays our efforts to fill this lack of understanding and provides both, an overview of our recent progress as well as a forecast of our future research.
Poly-ε-caprolactone and polylactic acids have been chosen to act as reference systems for our research, in which we aim to create polyesters of the same HHB but of varying crystallinity. In order to accomplish this, we generated different copolyesters with the same HHB as our reference polyesters. It was possible to obtain NP suspensions with controlled NP diameters from both homo- and copolymer systems that remained stable over weeks. The TPs of the NPs and the bulk material have been investigated via DSC, their mechanical properties as well as their morphology and stability in suspension via AFM and DLS. Additionally electron microscopy techniques like SEM and TEM were utilized for structural elucidation. Finally, pyrene fluorescence was performed to trace changes of the HHB.
Our results, supported by various techniques, demonstrate clearly that it is possible to change the TPs of polyesters and polyester based NPs while keeping the HHB constant. Based on these findings we will perform experiments upon the degradation behaviour, the drug uptake and the drug release of those polymer systems, depending on their TPs.
These polymeric NPs will lay the foundation for a new type of polymeric drug delivery systems, which allows tailoring the degradation and release kinetics by changing their TPs.
This work is part of the Collaborative Research Center 1278: “Polytarget: Polymer-based nanoparticle libraries for targeted anti-inflammatory strategies” – project A06 which is funded by the Deutsche Forschungsgemeinschaft (DFG).